1. Compared with non-exercises, women who exercised during pregnancy were less likely to require an acute C-section during their first delivery.
2. High-impact and frequent exercise were associated with the greatest reduction in cesarean deliveries.
Evidence Rating Level: 1 (Excellent)
Study Rundown: In the United States roughly 1 in 3 women deliver by C-section, which is a rate nearly twice what the World Health Organization recommends. While in some cases cesarean deliveries are medically necessary for both mothers and babies, they are major abdominal surgeries, requiring a longer recovery than vaginal deliveries. Additionally, risks of bleeding, infection, and damage to other organs are increased. Additionally, studies show that babies born by vaginal delivery experience improved respiratory outcomes. For these reasons, there’s an initiative to reduce cesarean delivery rates in developed countries worldwide, including identifying modifiable risk factors. Regular exercise has been shown to reduce risks of gestational diabetes, preeclampsia and excessive birthweight, all of which have been linked to increased likelihood of cesarean delivery. Studies looking directly at how exercise impacts cesarean delivery rates, however, have been limited and inconclusive. In this large, population-based cohort study, researchers looked at the relationship between exercise of various intensity during pregnancy and cesarean delivery in nulliparous women.
Compared with non-exercisers, women who exercised during pregnancy were less likely to require a C-section during their first delivery. Strengths of this study include the large sample size and national health record, which makes it easy to get accurate, large volume, birth outcome data. Overall cesarean section rates were much lower in this Norwegian cohort compared with the US population (15% vs. 30%), so results may not be generalizable to the US population. Futures studies might try to replicate these findings in other health care systems and patient populations.
Click to read the study in AJOG
Relevant Reading: Caesarean section without medical indications is associated with an increased risk of adverse short-term maternal outcomes
In-Depth [prospective cohort]: Nulliparous women with a singleton pregnancy who were enrolled in the Norwegian Mother and Child Cohort Study from 2000-2009 (n=39.187) were included in the analysis. Participants prospectively answered questionnaires that assessed exercise frequency and type at weeks 17 and 30 of gestation. The primary outcome was need for cesarean delivery (acute or elective), obtained from the Norwegian national birth registry.
The overall cesarean delivery rate was 15.4%. Of these, 77.4% were acute cesarean deliveries, meaning the decision was made <8 hours before the delivery. Women who exercised during pregnancy were less likely to require a cesarean delivery, particularly an acute cesarean delivery. The largest reduction in risk of cesarean was seen in women who exercised more than 5 times per week during weeks 17 (-2.2%, p = 0.004) and 30 (-3.6%, p < 0.001) of gestation (trend: p < 0.001). High-impact exercise was associated with the greatest reduced risk of acute cesarean delivery (-3.0% at 17 weeks, -3.4% at 30 weeks, p < 0.01 for both).
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